Incandescent lamp



F. A. FELDKAMP.. INCANDESCENT LAMP.

APPLICATION HLED ssPLza, 1919.

1,438,807, Patented Oct. 31, 1922.

INVENTOR ATTO R N EYS Patented Oct. 31, 1922.

UNITED STATES Param"v OFFICE.

FREDERICK A. FELDKAIP, 0F NEWARK, NEW JERSEY, ASSIGNOR 0E ONE-HALF T0 RUDOLF H. AIBERG, OF BLOOMFIELD, NEW JERSEY.

INCAN DESCENT LAMP.

Application led September 26, 1919". Serial No. 326,466.

To all whom t may concern:

Be it known that I, Fnnnnmcx A. 'FELD-i KAMP, a citizen of the United States, residing,

acters of reference -markedthereom which form a part of this specification.

The present invention relates, generally, to improvements in incandescent electrlc lamps; and the invention has reference, more particularly, to a novel construction of double filament lamp provided with an automatic means operating to bring into the lamp circuit one filament after the other filament has burned out or broken. p

The invention has for its principal object to provide a novel construction of double 'filament incandescent lamp having a novel automatic switching mechanism for inserting operatively into the lamp circuit Vone fi1ament,`and upon the burning out of said filament automatically bringing into the lamp circuit the second filament, whereby 4either the .life length of the lamp as a whole is doubled, or the efficiency of the lamp in, its lighting effects is greatly increased with a life length substantially that vof a single filament lamp. l

Other objects of the present invention, not at this time more particularly enumerated, will be clearl understood from the followin detailed escription of the same.

ith the various ob'ects of the invention in view, the same consists, primarily, in the novel construction of incandescent lamp hereinafter set forth; and the invention lconsists, furthermore, in the novel arrangements and combinations of the various devices and parts, as well as in the details of the construction of the same, all of which will be hereinafter more fully described, and then finally embodied in the appended claims. l

The invention is clearly illustrated in the accompanying drawings, in which Figure 1 is an elevation of my novel incandescent lamp, a portion of the enclosing bulb being shown in section, the same illustrat'ing the automatic switch mechanism as normally arranged tohold in the lamp circuit for service one of the two filaments employed therewith; Figure 2 is a similar view illustrating the switch mechanism, as automatically operated upon the burning out of the first filament, serving to switch into the lamp circuit for service the second filament. Figure 3 is a detail view, similar to that shown in Figure 1, but illustrating a slightly modified form of automatic switch mechanism. yFigure 4 is a diagram illustrating the electrical arrangement and operative relation of the switching mechanism to the two filaments of the lamp. t

Similar characters of reference are employed in all of the hereinabove described views, to indicate corresponding parts.

Referring now to said dra-wings, the reference-character 1 indicates the usual glass.

bulb which 'encloses the filaments, the same being provided with the usual screw-threaded plug 2 and center button contact 3 for insertion in a socket to electrically connect the leading-in wires 4 and 5 of the lamp in the operating electric supply circuit. Mounted to extend upwardly within the interior of the bulb 1 is the hollow glass stem 6 through which the said wires 4 and 5 extend, said glass stem 6 carrying an upwardly extending supporting post or rod 7 of glass for -supporting the filaments within the bulb.A

Two filament members are supported from said supporting post or rod 7 by bracket pieces 8 which are fused into said post or rod so as to radiate therefrom, each of said filament members being electrically connected on one side to the leading-in wire 4 by means of the interconnecting wire `conductor 9. The filament member to be first used in service comprises a two branch filament, to wit` the filament'branch 10 and the filament branch 11, each branch being of one-half the total candle power and wattage desired of the complete filament member, but each branch' being lcapable of operating. at the line voltage intended for the compfete filament member. The said branches 10 and 11 are respectively connected, by the ends thereof opposite the ends connected with said leading-in wire 4, to the upper end of a conducting wire and support 12 which extends( is outwardly and laterally offset from the,

latter.

Mounted on said glass stem 6 by means of a suitable embracing clamp device 17 is an upwardly extending spring-,arm 18 terminating at its upper or free end in a lateral or transverse contact arm 19, which, when the spring-arm is held under tension, is caused to electrically contact with or engage said' conducting wire and support 12, to connect said first filament member through Said? spring arm, which is a conductor, wlth the leading-in wire 5, the latter being electrically conducted with said spring-arm by means of an interconnecting wire conductor 20 and said contact arm 19, when the springarm is released, is caused to electricallycontact with or engage said conducting wire and support 15, to connect said second filam'entmember with said leading-in wire 5. Said spring-arm 18 is compounded with an auxiliary or secondary spring-arm 21, the base of the latter being suitably secured to the body of' said main spring-arm 18, so that said auxiliary or secondary spring-arm 21 extends upwardly beyond the location of said contact-arm. 19 of said main sprin arm. The upper' or free end of said auxi iary or secondary spring-arm is provided with a coa-ting of insulating material, such, for example, as the bead 22 of glass, or similar material.

The branch 10 of said first filament member is tapped midway between its ends by a tap-wire 23, and the branch 1l of said first filament member is tapped midway between its ends by a tap-wire 24. Connected with and extending outwardly from said post or rod 7 is a bracket piece 25 to which one end of a fuse link or wire 26'is anchored and at the same time electrically connected with said tap-wire 23, and also connected with and extending oppositely outward from said post or rod 7 is another bracket piece 27 to which the opposite end of said fuse link or wire 26 is anchored and at the same time electrically connected with said tap-wire 24, Said fuse link or wire 26 extends around the insulating bead 22 of said auxiliary springarm 21, holding the latter under tension, and at the same time holding the main spring-arm 18 under tension and in position to electrically engage the contact-arm 19 with the wire and support 12, thus switching into and maintaining in Service the first filament member, while the circuit through the second filament is interrupted to render the latter inoperative or out of service. The purpose of the auxiliary spring-arm 2l is to provide a means for compensating any slight f release of the tension, under which 'the main sprin -arm 18 is to be held in order to maintain t e contact arm 19 in operative electrical engagement with the wire and support 12,

which might be caused by slight expansion or elongation'of the fuse link or wire under the normal temperature increase within the bulk when the lamp is lighted, and which,

did not the auxiliary spring-arm 21 compensate for," might result in the separation of the contact arm 19 from the wire and support 12 thereby interrupting the circuit through the first filament member, without fully releasing the spring-arm 18 to carry the contact-arm 19 into circuit closing relation to the wire and support 15 and secondv filament member.

The lamp constructed, as above described, 90 is intended to operate as 'followsz-Normally the first filament is held in circuit and consequently in service. The current flows through the two branch filaments 10 and 11, which vbeing of equal capacity and resistance carry the current fiow so equally that there exists no tendency of the current to shunt through the fuse link or wire 26 by way of the tap wires v23 and 24, and consequently the fuse link or wire remains intact 100 and serves its purpose of mechanically tying back the spring-arms 18 and 21 in the position completing the circuit through said first filament member.. If, however, the first filament breaks in either of its branches 10 or 105 11 (by reason of burning out or from other causes), then the balance of current flow through the said filament branches 10 and 11 is disturbed so that some of the current is passed through the fuse link or wire 26, causing the latter to immediately blow and break so that the spring-arms 21 and 18 are released, whereby the spring-arm 18 swings outward, under the impulse of its tension, to carry the contact-arm 19 away from the 1]5 wire and support 12 and into electrical engagement with the wire and support 15 so that the second filament member is immediately switched in to circuit and service, and the life ofthe lamp is thereby extended.

In order to'provide a Aclear understanding of the electrical operations and functioning involved in my present invention, reference may be had .to ythe diagram shown in Figure 4. As indicated in said diagram, cur-'125 rent normally flows through 9-10-11--12f 18, this fiow being balanced in the branches4 10a-nd 11 so that no current fiows lthrough 23-26-24. Assume, however, that the first filament member breaks in branch 10 at 130 Ies will fiow from 9 to 12-18 through c -d of branch 11, and also through c-24-26-- 23-b. Ifl the breaks occurs in branch 10 at -bthen' 4the current will flow through c-d, and also through a-23-26-24-d. If the break occurs in branch 11 at -c-, then the current will flow through al-b, and

if the break occurs in branch 11 at -d-, then the current will fiow through a-b, and also through 0 24-26--23-6. It is therefore apparent that any of these breaks will cause a blowing of the fuse link or wire 26, since the current passed therethrough will be sufficient for that pu ose. The amount of current rendered available for blowing the fuse link or wire 26 may be exemplified by the following instance, based on the performance of a 200 watt-100 volt lamp.

Assuming that the combined amperage of the two branched filament 10-11 is 2 amperes. The resistance of each branch 10 and 11 respectively, is 100 ohms, and consequently for each part a, b, c and d is 50 ohms. If the two branches 10 and 11 respectively operate properly, they each consume l ampere at 100 volts. In the vevent a break occurs in any of the portions a, b, c or d of the said branches 10 and 11, it follows, that there will always be two portions of 50 ohms each in parallel, connected inseries with one portion of 50 ohms. T he resistance of such a series or combination therefore will be 25 plus 5() or 75 ohms. This means that there are 1.33 amperes flowing, and onehalf of this amount will pass through thev fuse link or wire 26, which is selected"accordingly to blow under such a condition. Of course, there is a small discrepancy in the example given, as after the break the temperature of the branches of filaments in series is not alike. The two branches in parallel are under normal and consequently their resistance is less, and the single remaining branch in series with the latter is overloaded, therefore its resistance is higher. While this condition tends to counterbalance, yet there isa change from initial normal condition in the series which will be sufficient to blow the fuse link'or wire 26 selected to meet the condition. The fuse link or wire 26 should be very 'fine so thatl elements or lateral arms 29 and 30 for respectively engaging the su porting conductors 12 and 15 of the respective filaments.

While I have illustrated my invention with the switching mechanism arranged Within the bulb, it will be clearly evident that the scope V'of my present invention will one side a common connection with one pole of the lamp, the first filament com rising a balanced two-branched filament the ranches of which are in parallel, a spring switch means in connection with the other poleof the lamp, a fuse link arranged to normally hold said spring switch means in circuit closing engagement with said first filament, and tap wires connecting the ends of said fuse link respectively with intermediate ortions of said first filament branches, sai spring switch means when released by the breaking of said fuse link being adapted to move into circuit closing engagement with the next filament. Y

2. In an incandescent lamp, the combination with a plurality of filaments, a nonconducting supporting rod from which said filaments are supported, a conducting means serving as a common connection between one side of said respective filaments and one pole of said lamp, a supporting conductor secured to said supporting rod for connection with the opposite side of the first filament, a sec- 0nd supporting conductor secured to said supporting rod 'for connection with the opposite side of the second filament, a sprin switch means in electrical connection wit the other pole of the lamp, a fusible means for holding said switch means in circuit closf ing engagement with the supporting conshunting current through said fusible means upon the breaking of said first filament whereby said fusible means breaks to release said switch means for circuit closing engagement with said supporting conductor of said second filament.

3. In an incandescent lamp, the combination with a plurality of filaments, -a nonconducting supporting means from which said filaments are supported, a conducting means serving as a common connection between one side of each filament and one' pole of said lamp, a supporting conductor secured to said supporting means for eonnection with the opposite side of said first filament, a second supporting conductor secured to said supporting means for connection with the opposite side of the second filament, a spring switch-arm secured to said supporting means and electrically connected with the opposite pole of said lamp, a fuse link, means for supporting said fuse linkfrom said supporting means, said fuse I5 link engaging the free end of said switch arm to hold the same under stored tension and in circuit closing engagement with said supporting conductor of said first filament, means for electrically insulating said switch arm from said fuse link, said first filament comprising a balanced twobranched'filament the branches of which are 'will shunt current through said fuse link to blow the same thereby releasing said switch arm for movement into circuit closing engagement with said csupporting conductor of said second filament.

4. In an incandescent lamp, the combination with 'a plurality of filaments, a nonconducting supporting means from which said filaments are supported, a conducting means serving as a common connection between one side of each filament and one pole of said lamp, a supporting conductor secured to said Supporting means for connection with the opposite side of said vfirst filament, a second supporting conductor secured to said supporting means for connection with the opposite side of the second filament, a spring switch arm secured to said supporting means and electrically connected with the opposite pole of said lamp, the free end of said switch arm having contact means, a secondary spring arm anchored upon said switch arm, a fuse-link, means forsupportingsaid fuse link from said supporting means, said fuse link engaging the free end of said secondary spring-arm to holdA same and said switch arm under stored tension and the latter in circuit closing engagement with said supportin conductor of said first .filament.sa1d secon aryspring arm serving -t0 conpensate any elongation of said fuse link due to expansionby heat, vmeans for electrically insulating said secondary spring arm from said fuse link, and means for electrically connecting said fuse link with said first filament so that breaking of the lati ter will shunt current through'said fuse link to blow the same thereby releasing said switch' arm for movement into circuit closing engagement with said supporting conductor of said second filament.

5. In an incandescent lamp., the combination with a plurality of filaments, a nonconducting supporting means from which said filaments are supported, a conducting means serving'oas a common connection between one side` of each filament and one pole of said lamp, a supporting'conductor secured to said supporting means for connection with the opposite side of said first filament, a secondsupporting conductor secured to said supporting means for connection with the opposite side of the second filament, a spring switch arm secured to said supporting means and electrically connected with the opposite pole of said lamp,the free end of said switch arm having contact means, a secondary spring arm vanchored upon said switch arm, a fuse-link, means for supporting said fuse link from said supporting means, sa-id fuse-link engaging the free end of said secondary spring-arm to hold same and said switch-arm under stored tension and the latter in circuit closing engagement with said supporting conductor of said first filament, said secondary springarm serving to compensate any elongation of said fuse-link due to expansion byf heat, means for electrically insulating said secondary spring arm from said fuse link, said first filament comprising a balanced twobranched fila-ment the branches of which are connected in parallel between said common conducting means on oneside and said first supporting conductor on the other side, and tap wires connecting the ends of said fuse link respectively with points intermediate the ends of each branch of said first filament to provide r*balanced filament portions on each side of each tap wire so that the breaking of any portion of either filament branch will shunt current through said fuse-link to blow the same thereby releasing said switch arm for movement into `:circuit closing engagement with said supporting conductor of said second filament.

6. In, an incandescent lamp, the combination with a pair of filaments of means for connectingy the latter with one pole of said Alamp, a spring switch arm electrically connected with the opposite pole of said'lamp,

means connected with each filament for receiving the circuit closing engagement of said switch arm therewith, a fuse-link, means for supporting said fuse-link, said fuse-link normally engaging said switch arm to hold the same under stored tension and in circuit closing relation to the first filament, means 'for insulating said fuse-link from said switch arm, and means for'electrically connecting said fuse-link with saidlfirst filament so that breaking of the latter will shunt current through said fuse-link to blow the same thereby releasing said switch arm forl movement into circuit closing relation to the second filament.

7. In an incandescent lamp, the combination with a pair of filaments of means for connecting-the latter with one pole of said lamp, a spring switch arm electricallyt connected wlth the opposite pole vof saidl lamp, means connected witheach filament for receiving the circuit closing engagement link with said first filament so that breakin of the latter will shunt current through sai 15 fuse-link to blow the same thereby releasing said switch arm for movement into circuit closingr relation to the second filament.

In testimony that I cla-im the invention set forth above I have hereunto set my hand 20 this 25th day of September. 1919.

FREDERICK A. FELDKAMP.

Witnesses:

GEORGE D. RICHARDS, BARBARA'W. SU'rmauN. 

